1. Field of the Invention
The present invention generally relates to methods for counting and staging of nucleated red blood cells (NRBC). More specifically, the present invention relates to the quality control and calibration of nucleated red blood cell counting and staging on automatic hematology analyzers, which allows the hematology analyzers to use the methods to ensure a mode of accurate and precise counting and staging. The invention is directed to using a new control material for nucleated red blood cell counting and staging.
2. Background Information
In a clinical laboratory, particularly when a cell analyzer is used, a calibrator and quality control material is necessary to enable the instrument to perform at a continuously optimal level to ensure accurate and precise results that can be reported.
For example, when using a hematology analyzer, fresh blood is used as a control material. Fixed blood and various types of latex beads are used to provide longer control times to observe any change in a given time frame and observe data results for any necessary calibration change.
Another calibration example can be viewed on a flow cytometer. To guarantee proper working conditions of the instrument, fluorescent labeled beads and animal blood have been used as control materials.
In normal situations of erythropoiesis, there are no nucleated red blood cells found in human peripheral blood except for a short time in neonate blood. When nucleated red blood cells found appear in peripheral blood, it is always an indication of a pathologic situation. Peripheral nucleated red blood cell counting is clinically useful in that it corrects for white blood cell counts and also gives clinicians a basis for diagnosis and prognosis of diseases using peripheral nucleated red blood cell blood. When nucleated red blood cells appear in the peripheral blood, they are counted as white blood cells with a traditional hematology analyzer. This count occurs due to the similar physical characteristics of the two types of cells. When nucleated red blood cells can be separated from white blood cells by a hematology analyzer, it can provide more accurate white blood cell numbers and important information for the diagnosis and prognosis of the diseases with peripheral blood nucleated red blood cells. Therefore, measurement of nucleated red blood cells is very important for clinicians to be able to decipher diseases more easily. This measurement can allow for a quicker diagnosis.
Traditionally, nucleated red blood cells have been counted using a manual method. However, these methods were laborious and time consuming. To obtain a more sensitive, faster, and a less expensive method, nucleated red blood cell measurement using automatic hematology analyzers, has been developed. To make sure the detection method can work correctly, a quality control material is necessary. The control material has to include cell populations of white blood cells and nucleated red blood cells, so that a nucleated red blood cell number, and a nucleated red blood cell count per 100 white blood cells, are available. The control material must also remain stable in order to monitor and to necessitate any change in calibration on a hematology analyzer.
In view of the above, there exists a need for the quality control and calibration of nucleated red blood cell counting and staging on automatic hematology analyzers. This methodology allows the hematology analyzers to use a desired method to ensure a mode of accurate and precise counting and staging which overcomes the above-mentioned problems in the existing art.
It is an objective of this invention to provide a new control material that can be used for nucleated red blood cell counting and staging.
The present invention provides methods for the quality control and calibration of nucleated red blood cell counting and staging. The methodology uses a new control material made from a mixture of human blood and chicken red blood cells, or fixed human blood alone.
(1) First, a preferred embodiment of the invention uses fixed chicken red blood cells with nuclei that can be used to provide fluorescent signals as seen in real human nucleated red blood cells.
(a) A fixed human peripheral blood sample from an SF-check, a control material for Sysmex hematology analyzers is used and mixed with chicken red blood cells, for example, from BioSure; and
(b) The mixed blood was tested on the hematology analyzer in different ways.
(2) Second, the mixture of fixed human blood and chicken blood is analyzed on an automated hematology analyzer, such as the XE-2100.
(3) Third, the diluted chicken red blood cells are measured using different concentrations in SF-check to analyze the linearity of nucleated red blood cells represented by chicken red blood cells.
(4) Fourth, nucleated red blood cell concentration is measured in different mixtures that included mixture with SF-check in high, normal and low concentrations, having the ratios of 1:1 to 1:9 to obtain the different nucleated red blood cell counting levels.
(5) Fifth, the mixture of blood is kept at 4xc2x0 C. in order to check the stability of the mixture and count the nucleated red blood cell number and nucleated red blood cell count per 100 white blood cells.
An alternate embodiment of the invention uses fixed human blood.
(1) The human blood, namely human peripheral blood, or umbilical cord blood, can be fixed with different types of fixing buffers, typically the commercial available ones, such as Cytocheck.
(2) The fixed human blood was tested on a hematology analyzer, like the XE-2100, to observe the scatter graphs, the nucleated red blood cell number and the nucleated red blood cell number per 100 white blood cells.
(3) The fixed blood is stored in different tubes or in ones tube with a large volume.
(4) The stored blood is tested on the hematology analyzer repeatedly, to observe the stability of nucleated red blood cell counting and staging.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.